Abstract

We report the observation of ultraviolet and visible near-resonance enhanced Raman scattering in epitaxial wurtzite (0001) thin films. The films were grown by plasma sourcemolecular beam epitaxy on sapphire (0001) substrates. A substantial spectral enhancement is seen for Al-rich samples using 244 nm (5.01 eV) radiation due to the closeness of their band gapenergy to the excitation energy. On the other hand, samples with (energyband gap show significant enhancement with 514.5 nm (2.41 eV) excitation. The and zone center phonons have been observed for all the samples. The phonon frequency shows the expected decrease with increasing The mode shows a two-mode behavior supporting the recent theoretical predictions. Due to increased resonance enhancement, strong second- and third-order spectra are seen in some films.